巧算1/1×2+1/2×3+1/3×4+…1/49×50
问题描述：
巧算1/1×2+1/2×3+1/3×4+…1/49×50
答
1/1×2+1/2×3+1/3×4+…1/49×50
=1-1/2+1/2-1/3+…+1/49-1/50
=1-1/50
=49/50